»The Snail-Watcher and other stories

I was delighted to find a copy of this anthology of Patricia Highsmith's short stories, collecting stories on a theme from 1945 to 1970. I have been looking for one of these, "The Quest for 'Blank Claveringi'", for some time, since reading it in another anthology (along what theme, I cannot recall; it may have been a science-fiction or horror book or magazine) when I was quite young. The story made a huge impression on me, for the economy of its language (although in re-reading it this morning, I needed to consult a dictionary for nacreous and crepitation) and for the inventiveness of its plot.
Most of these stories do not appear in either of the two recent paperback anthologies.